<!doctype html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<canvas id="myCanvas" width="300" height="200"></canvas>
<script type="text/javascript">
var ctx = document.getElementById('myCanvas').getContext('2d');
var radgrad = ctx.createRadialGradient(55,55,20,100,100,90);
radgrad.addColorStop(0,'#ffffff');
radgrad.addColorStop(0.75,'#333333');
radgrad.addColorStop(1,'#000000');
ctx.fillStyle = radgrad;
ctx.fillRect(10,10,200,200); 

</script>
</body>
</html>  
